JP2019030277A - Hand-held engine working machine - Google Patents

Abstract

To provide a hand-held engine working machine provided with an engine in the rear end of a support pole such as a bush-cutter, in which an upper surface of a plug cap for covering a head of a spark plug is prevented from becoming a high temperature.SOLUTION: A hand-held engine bush-cutter 10 includes an engine 20 provided at the rear end of a support pole 11, a driven unit 12 provided at the front end of the support pole 11 and driven by the engine 20, and an operating handle 14 (14a, 14b) provided at a longitudinal intermediate part of support pole 11 and gripped by a worker. A spark plug 30 for igniting a combustion chamber 25 is arranged in the front part of the engine 20, and a plug cap 31 for covering up this is arranged in the upper part of the spark plug 30. A thermal insulation unit 31c having a thermal insulation air layer 31d is included between an upper surface of the plug cap 31 and a position where the head of the spark plug 30 is arranged.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a hand-held engine working machine including an engine at a rear end portion of a support rod such as a brush cutter.

  Patent Document 1 discloses an invention of a brush cutter. The brush cutter of Patent Document 1 includes an engine provided at a rear end portion of a support rod, a rotary blade provided at a front end portion of the support rod, and a power provided inside the support rod to transmit driving of the engine to the rotary blade. A transmission shaft and an operation handle provided at an intermediate portion in the front-rear direction of the support rod and gripped by an operator. The drive of the engine is transmitted to the rotary blade by the power transmission shaft, and the rotary blade rotates by receiving the drive of the engine at the front end portion of the support rod. When mowing with this brush cutter, the operator holds the operating handle so that the support rod extends obliquely forward and backward on the side of the operator, and sets the rotary blade that rotates at the front end of the support rod to the ground. The grass that grows on the ground is mowed by swinging left and right along.

JP 2013-050084 A

  In the brush cutter of Patent Document 1, when the engine provided at the rear end portion of the support rod is driven, the engine becomes high temperature by burning fuel in the combustion chamber, and the heat in the combustion chamber is increased by the engine. It is also transmitted to the spark plug provided at the front of the. Although the spark plug cap is provided at the head of the spark plug, the rubber plug cap sometimes becomes high temperature due to the heat of the combustion chamber transmitted through the spark plug. When mowing the grip with the operating handle so that the support rod extends obliquely back and forth on the side of the operator, the elbow of the arm that grips the handle is located near the engine at the rear end of the support rod Therefore, there was a possibility that the elbow might come into contact with the plug cap that became hot. The present invention is a hand-held engine working machine provided with an engine at the rear end of a support rod such as a brush cutter, and prevents the upper surface of the plug cap covering the head of the spark plug from becoming hot. Objective.

  In order to solve the above problems, the present invention provides an engine provided at a rear end portion of a support rod, a driven portion provided at a front end portion of the support rod and driven by the engine, and a longitudinal direction of the support rod. A hand-held engine working machine provided with an operation handle provided at an intermediate portion and gripped by an operator, with an ignition plug for igniting a combustion chamber at the front of the engine and an ignition plug at the head of the ignition plug A hand-held engine working machine comprising a heat insulating part having a heat insulating air layer between a top surface of the plug cap and a position where the head of the spark plug is disposed. It is to provide.

  In the hand-held engine working machine configured as described above, when an operator works using the hand-held engine working machine while holding the operation handle so that the support rod extends back and forth on the side of the operator In addition, the elbow of the arm of the operator holding the operation handle may come into contact with the plug cap of the engine provided at the rear end of the support rod. In this hand-held engine working machine, the heat of the combustion chamber when the engine is driven is transmitted to the plug cap covering the spark plug and the head of the spark plug, but the upper surface of the plug cap and the head of the spark plug are arranged. Since the heat insulating part having the heat insulating air layer is provided between the two positions, the upper surface of the plug cap can be prevented from becoming hot.

  In one embodiment of the hand-held engine working machine configured as described above, the heat insulating air layer of the heat insulating portion may be formed by a recess or a through hole formed below the upper surface of the plug cap. In another embodiment of the hand-held engine working machine, the heat insulating air layer of the heat insulating portion may be formed by a recess formed on the upper surface of the plug cap.

It is a perspective view of the handheld engine brush cutter which is one Embodiment of the handheld engine working machine of this invention. It is a longitudinal cross-sectional view along the front-back direction of an engine. It is a perspective view of a plug cap. It is a side view of a plug cap. It is AA sectional drawing. It is a side view of the plug cap of other embodiment.

  Hereinafter, a handheld engine brush cutter which is an embodiment of the handheld engine working machine of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the handheld engine brush cutter 10 includes an elongated cylindrical support rod 11 extending in the front-rear direction, a cutter unit (driven portion) 12 provided at the front end of the support rod 11, An engine 20 provided at the rear end of the support rod 11, a power transmission shaft 13 provided inside the support rod 11 for transmitting the drive of the engine 20 to the cutter unit 12, and an intermediate portion in the front-rear direction of the support rod 11. And an operation handle 14 held by an operator.

  As shown in FIG. 1, the cutter unit 12 includes a front end housing 12 a fixed to the front end of the support rod 11. A rotary shaft (not shown) that protrudes downward is rotatably supported in the front end housing 12a, and a rotary blade 12b is attached to the tip of the rotary shaft at the lower side of the front end housing 12a. A bevel gear is fixed in the front end housing 12a to the base end portion of the rotating shaft, and a bevel gear fixed to the tip of the power transmission shaft 13 is engaged with the bevel gear. The power transmission shaft 13 is rotated by driving an engine, which will be described later, and the rotation of the power transmission shaft 13 is transmitted to the rotation shaft by a bevel gear pair, and the rotary blade 12b rotates together with the rotation shaft.

  As shown in FIG. 1, an operation handle 14 held by an operator is provided at an intermediate portion in the front-rear direction of the support rod 11. The operation handle 14 of this embodiment includes a loop handle 14 a formed in an annular shape. A grip handle 14b provided on the support rod 11 on the rear side of the loop handle 14a. The grip handle 14b is provided with a trigger switch 14c, and the engine 20 is driven by the operation of the trigger switch 14c. The operation handle 14 is not limited to the loop handle 14a and the grip handle 14b described above, but may be a U-shaped handle having a substantially U shape.

  As shown in FIG. 2, the engine 20 includes a known internal combustion engine, and includes an engine body 21 and an engine case 22 that covers the engine body 21. The engine body 21 includes a cylinder block 23 integrally provided with a crank housing 23a at the lower portion and a cylinder 23b at the upper portion, and a piston 24 is accommodated in the cylinder block 23 so as to reciprocate in the vertical direction. A combustion chamber 25 is formed between the upper surface of the piston 24 and the cylinder head 23 c at the upper end of the cylinder block 23. The cylinder head 23c is provided with an intake port that guides the air-fuel mixture generated by the carburetor to the combustion chamber 25 and an exhaust port that guides exhaust gas generated in the combustion chamber 25 to the exhaust muffler (both not shown).

  A crankshaft 26 is provided in the crank housing 23a, and the crankshaft 26 is supported so as to be rotatable around an axis whose front-rear direction is an axial direction. A piston 24 is connected to the crankshaft 26 via a connecting rod 27, and the reciprocating motion of the piston 24 in the vertical direction is converted into the rotational motion of the crankshaft 26. A flywheel 28 is provided at the front end of the crankshaft 26, and the flywheel 28 has a function of stabilizing the rotation of the crankshaft 26 and cooling the inside of the engine 20. A centrifugal clutch 29 is provided at the front end of the crankshaft 26 on the front side of the flywheel 28. The centrifugal clutch 29 supports the rotation of the crankshaft 26 when the rotational speed of the crankshaft 26 exceeds a predetermined value. It is transmitted to the power transmission shaft 13.

  As shown in FIG. 2, a plug hole 23d that is inclined obliquely forward is formed in the front portion of the cylinder head 22c, and a spark plug 30 is detachably attached to the plug hole 23d. The spark plug 30 ignites the air-fuel mixture in the combustion chamber 25 by spark discharge. A plug terminal 30a is provided at the head of the spark plug 30, and a cord (not shown) for supplying a high voltage current generated by an ignition coil or the like is connected to the plug terminal 30a. The spark plug 30 can be taken out upward from a hole 22a formed in the front portion of the engine case 22, and a plug cap 31 is detachably attached to the head of the spark plug 30.

  As shown in FIGS. 2 to 4, the plug cap 31 protects the plug terminal 30 a and the cord connected thereto, and prevents the operator from directly touching the spark plug 30 exposed from the hole 22 a of the engine case 22. The purpose is to make it. The plug cap 31 has a cylindrical fitting attachment portion 31a that is fitted and attached to the head of the spark plug 30, and a cylindrical cord protection portion 31b that communicates with the upper portion of the fitting attachment portion 31a to protect the cord. And a heat insulating part 31c provided on the upper side of the fitting attachment part 31a and the cord protection part 31b and suppressing the heat of the combustion chamber 25 from being transmitted to the outside through the spark plug 30, and these are made of an elastic material such as rubber. It is formed integrally using members.

  The heat insulating portion 31c is formed in a thick plate shape between the upper surface of the plug cap 30 and the fitting mounting portion 31a that is the position where the head of the spark plug 30 is disposed. The heat insulating portion 31c is formed with a heat insulating air layer 31d made of a concave portion on both sides in the left-right direction below the upper surface of the plug cap 31, and this heat insulating air layer 31d has a function of enhancing the heat insulating effect of the heat insulating portion 31c. doing. In addition, although this heat insulation air layer 31d consists of the recessed part formed in the right and left both sides of the heat insulation part 31c, it is not restricted to this, You may be made into the through-hole which penetrates both right and left sides.

  The mowing work using the handheld engine brush cutter 10 configured as described above will be described. The operator who performs mowing work holds the loop handle 14a with the left hand and the grip handle 14b with the right hand so that the support rod 11 extends forward and backward on the right side (lateral side) of the operator. When the trigger switch 14c is operated with the finger of the right hand holding the grip handle 14b, the rotary blade 12b rotates by receiving the drive of the engine 20 at the front end portion of the support rod 11. When the rotary blade 12b rotating at the front end portion of the support rod 11 is swung left and right along the grassy ground, the grass growing on the ground is cut by the rotating rotary blade 12b.

  In the hand-held engine brush cutter 10 configured as described above, when the engine 20 provided at the rear end of the support rod 11 is driven, the engine 20 burns the air-fuel mixture (fuel) in the combustion chamber 25. As a result, the temperature becomes high, and the heat in the combustion chamber 25 is also transmitted to the spark plug 30. The heat transmitted to the spark plug 30 is also transmitted to the rubber plug cap 31. As described above, the operator who performs the mowing work grips the grip handle 14b when he / she holds the operating handles 14a and 14b so that the support rod 11 extends back and forth on the side of the operator. There is a possibility that the elbow of the arm of the operator who touches may contact the plug cap 31 of the engine 20 provided at the rear end of the support rod 11.

  In this hand-held engine brush cutter 10, a spark plug 30 is disposed at the front of the engine 20 provided at the rear end of the support rod 11, and a plug cap 31 is disposed at the head of the spark plug 30 to cover the spark plug 30. A heat insulating part 31c having a heat insulating air layer 31d is provided between the upper surface of the plug cap 31 and the position where the head of the spark plug 30 is disposed. By doing so, it is possible to prevent the upper surface of the plug cap 31 from becoming hot, and even if the elbow of the arm that grips the grip handle 14b of the operator who performs mowing work contacts the plug cap 31, the grip handle It was possible to prevent the elbow of the arm holding 14b from getting hot.

  In the handheld engine brush cutter 10 of the above embodiment, the heat insulating air layer 31d of the heat insulating portion 31c is formed by the concave portion formed below the upper surface of the plug cap 31, but the present invention is not limited to this. As shown in FIG. 6, the heat insulating air layer 31 d of the heat insulating portion 31 c may be formed by a recess (shown by a broken line in the drawing) formed on the upper surface of the plug cap 31.

  Although the present invention has been described using the handheld engine brush cutter 10 as one embodiment of the handheld engine working machine, the present invention is not limited to this, and an engine provided at the rear end of the support rod, A cutter unit comprising a guide bar and a saw chain provided at the front end portion of the support rod and driven by the engine, and an operation handle provided at an intermediate portion in the front-rear direction of the support rod and gripped by the operator It may be a hand-held engine working machine such as a hand-held engine pole saw equipped with.

  DESCRIPTION OF SYMBOLS 10 ... Hand-held engine working machine (hand-held engine brush cutter), 11 ... Support rod, 12 ... Driven part (cutter unit), 14 (14a, 14b) ... Operation handle (loop handle, grip handle), 20 ... Engine 25 ... Combustion chamber, 30 ... Spark plug, 31 ... Plug cap, 31d ... Insulating air layer.

Claims (3)

An engine provided at the rear end of the support rod;
A driven portion provided at a front end portion of the support rod and driven by the engine;
A hand-held engine working machine provided with an operation handle provided at an intermediate portion in the front-rear direction of the support rod and gripped by an operator;
A spark plug that ignites a combustion chamber and a plug cap that covers the spark plug at the head thereof are disposed at the front of the engine.
A hand-held engine working machine comprising a heat insulating portion having a heat insulating air layer between an upper surface of the plug cap and a position where a head of the spark plug is disposed. The hand-held engine working machine according to claim 1,
A hand-held engine working machine, wherein a heat insulating air layer of the heat insulating portion is formed by a concave portion or a through hole formed below the upper surface of the plug cap. The hand-held engine working machine according to claim 1,
A hand-held engine working machine, wherein a heat insulating air layer of the heat insulating portion is formed by a concave portion formed on an upper surface of the plug cap.

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